Radiocarbon detection with quantum cascade laser based cavity ring-down spectroscopy

With the latest advances in mid- infrared (IR) technology emerge new spectroscopic applications. Amongst other, optical radiocarbon detection allows for real-time, on-site leak detection in nuclear facilities. Natural abundance of the radiocarbon in ambient air is about ¹⁴C/¹²C = 1.2 ppt, whereas it can reach low ppm levels in radioactive waste repositories. Radiocarbon is present in all parts of nuclear power plants and is potentially subject for release, mostly in the form of carbon dioxide. The current state-of-the-art in ¹⁴CO₂ monitoring is Accelerator Mass Spectrometry and Liquid Scintillation Counting techniques. However, both techniques are limited to lab-based analysis, requiring complex and time consuming sample treatment and measurement procedures. Optical radiocarbon detection has been studied for nearly 40 years, and high sensitivity was achieved in the past few years by intracavity optogalvanic and saturated absorption Cavity Ring-down Spectroscopy (CRDS) techniques. Both techniques require too large light sources to be implemented for in-situ measurements.